As a Columbia Heights resident who often visits his Mount Pleasant brother and friends, I feel your pain and have long shared your curiosity. The story, according to a thorough treatment of the subject put out by the Historical Society of Washington in 2002, begins after the Civil War, when rapid population growth and an expanding streetcar network led developers to look beyond the traditional borders of the city. The 1791 L’Enfant plan that guided the District’s development only applied to what was then called the City of Washington, whose northern border was Boundary Road (now Florida Avenue). As investors saw increasing value in the outlying areas, dubbed the County of Washington, they began subdividing their plots into smaller areas for development. But these developers weren’t bound by the grid restrictions of the center city; instead, they aligned their roads according to topography and development needs.
One of these newly attractive areas was the Mount Pleasant subdivision, whose development was begun by Samuel P. Brown as early as the mid-1860s. The existing streets in the area were already oriented around hills and valleys more than cardinal directions: The main artery was the redundantly named 14th Street Road, which at the time ran due north until turning to follow a ravine northwest along a route that’s now Ogden Street, and Peirce’s Mill Road (today’s Pierce Mill Road is a corruption), which became Park Street and later Park Road, ran at an oblique northwest angle from 14th to Old Piney Branch Road.
So when Brown started developing in earnest and wanted to maximize the number of lots, he created new streets parallel to Park, including Sheridan Avenue (now Monroe Street), Howard Avenue (Newton Street), and Grant Street (Lamont Street).
East of 14th Street, an extension of Park Street called Whitney Avenue angled northeast and was joined by a parallel road to the north called Lydecker Avenue, now Monroe Street. It’s safe to assume these roads were also topographically aligned, given that they form a ridge that drops off as you go northward toward Spring Road.
In 1888, Congress passed legislation to regulate subdivisions throughout the District, and the new rules stipulated that “whenever practicable, streets and avenues will be in exact alignment with the streets and avenues of the city of Washington.” Even before the bill had passed, an 1887 announcement of new plans to develop Petworth expressed the developers’ desire to see their new subdivision “correspond with the lines of the streets and avenues of the city.”
Not all of the subdivisions developed before 1888 kept their peculiarly angled streets. “In some cases, the streets were realigned to conform with the grid,” says Surveyor of the District of Columbia Roland Dreist. “But in a lot of cases, you already had development on those diagonal streets, probably pretty nice homes, so you could hardly go through and knock down a whole subdivision of 50 homes.”
Unfortunately for all the folks toting their mandolins and freshly canned preserves across 14th Street, Mt. Pleasant was among the latter.